For me F8 is ground mount while ctrl+F8 is flying mounts. Sometimes on a cliff I have pressed just F8 and gone running off the edge to splat on the ground. I've dopne this once while grouped with my mboxing mate who just laughed at me.

Also, while playing solo on my druid, I've jumped off Aldor rise, planning to shift into flight form, but I died cos I was mashing seal form and wondering I kept getting an error message